The sustained and steady development of China’s economy has led to the rapid improvement of the logistics. At the same time, the rise of the e-commerce mode has given rise to a huge demand for express delivery and the express industry has entered a period of boom. Fortunately, China’s high-speed rail network has been networked, and the development of a high-speed rail express train has entered the test stage. After the high-speed rail express train is put into use, it could effectively relieve the pressure of highway transportation and significantly reduce transport pollution. To make better use of high-speed rail transport resources and give full play to its green and efficient advantages, this study established a two-stage model of a high-speed rail express train operation plan. In the first stage, a train candidate set generation model aiming for the minimum total cost of train operation was established that considered the high-speed line carrying capacity, section flow capacity, and OD requirement satisfaction constraints, which reduces the scale of train spare parts and improves the efficiency of solution. In addition, a column generation algorithm was designed to solve the model. In the second stage, an accurate flow distribution model aiming for the optimal economic efficiency was established, and then the high-speed express train operation plan was designed completely. The computational results are encouraging and demonstrate the effectiveness of the model and solution methodRead More

In order to understand the carbon fate of alpine peatlands under climate change, this study aimed to measure carbon accumulation in recent decades and that during the Holocene at seven representative peat sites on the Zoige Plateau using empirical peat core data (14C and 137CS) and modeling approaches. The observed apparent carbon accumulation rate over the past 50 years was 75 (35â€“123) g C mâˆ’2 yrâˆ’1, nearly four times that of 19 (7â€“30) g C mâˆ’2 yrâˆ’1over the whole Holocene. With decomposition history included in consideration by using modeling approaches, the average expected peat carbon accumulation rate was still nearly 1.6 times that of the modeled net carbon uptake rate of peats accumulated over the whole Holocene, though exceptions were found for Denahequ and Hongyuan peat cores with extremely low water table levels. The newly accumulated peat carbon of the Zoige Plateau amounted to 0.4 Tg C yrâˆ’1 (1 Tg = 1012 g) during recent decades. Overall, the effect of climate warming on recent C accumulation of peatlands on the Zoige Plateau is dependent on their water conditions. The peat C storage on the alpine Plateau is threatened by human activities (drainage) and continuous climate change with increasing temperature and decreasing precipitation which cause dryness of peatlandsRead More

Understanding the responses of the carbon-rich peatland ecosystems to past climate change is crucial for predicting peat carbon fate in the future. Here we presented a data synthesis of peatland initiation ages, area changes, and peat carbon (C) accumulation rate variations in China since the Holocene, along with total C pool estimates. The data showed different controls of peatland expansion and C accumulation in different regions. The peat C accumulation rates were 32.3 (ranging from 20.7 to 50.2) g C m-2 yr-1 in the Qinghai-Tibetan Plateau (QTP) and 14.7 (ranging from 7.4 to 36.5) g C m-2 yr-1 in the Northeast China (NEC). The peaks of peatland expansion and C accumulation in the QTP occurred in the early Holocene in response to high summer insolation and strong summer-winter climate seasonality. The rapid peatland expansion and maximum C accumulation rate in the NEC occurred in the middle-late Holocene. Peatlands scattered in the coastal and lakeside regions of China expanded rapidly at the onset of the Holocene due to large transgression, consistent with the stronger summer insolation and monsoon, and during the middle and late Holocene, as a response to the high and stable sea level and the strong summer monsoon. The carbon storage of peatlands in China was estimated as 2.17 (ranging from 1.16 to 3.18) Pg, among which 1.49 (ranging from 0.58 to 2.40) Pg was contributed by peatlands in the QTP, 0.21 (ranging from 0.11 to 0.31) Pg by those in the NEC, and 0.47Pg by those scattered in other regions of China. Our comparison of peatlands dynamics among regions in China showed that climate and monsoon are the essential factors in determining the expansion and carbon accumulation patterns of peatlands, although their effects on peatland formation and C accumulation is complex owing to land availability in peatland basins and regional moisture conditionsRead More

Most studies about carbon dynamics of peatlands have been focused on boreal, subarctic and tropical peatlands. However, there is limited data about carbon dynamics of alpine peatlands, like Zoige peatlands on the Qinghai-Tibetan Plateau (QTP), which are sensitive to climate change and human disturbance. We studied the role of these peat deposits on the Zoige as a C reserve and sink by measuring peat depth, radiocarbon age and peat and C accumulation rates at 7 sites. The peat depths of the sample sites ranged from 0.20 to 6.0m; the basal age on the plateau varied from 1635 to 14095calyr BP; the peataccumulation rates ranged from 0.12 to 0.85mmyr-1, and the C accumulation rates from 5 to 48 g m-2 yr-1. Based on data of field studies and remote sensing, we regarded that with 3179km2 of intact peatlands, about 1426km2 of degraded peatlands, and the total area of Zoige peatlands was 4605km2. The current peat C stock of Zoige peatlands was0.477Pg (ranging from 0.206 to 0.672Pg). We also estimated that peatlands covered an area of about 5091 km2on the QTP and sequestered 0.543PgC, 88% in Zoige and the rest in other parts of the plateau. Human activities, together with the ubiquitous warming on the plateau (temperature increased by 0.2°C per decade over the past 50 years) not only shrank the area of intact peatlands, but also caused substantial carbon releasing from peatlands.Read More

To understand spatial and temporal variations of nitrous oxide (N2O) fluxes, we chose to measure N2O emissions from three plant stands (Kobresia tibetica, Carex muliensis, and Eleocharis valleculosa stands) in an open fen on the northeastern Qinghai–Tibetan plateau during the growing seasons from 2005 to 2007. The overall mean N2O emission rate was about 0.018 ± 0.056 mg N m−2 h−1 during the growing seasons from 2005 to 2007, with highly spatiotemporal variations. The hummock (K. tibetica stand) emitted N2O at the highest rate about 0.025 ± 0.051 mg N m−2 h−1, followed by the hollow stands: the E. valleculosa stand about 0.012 ± 0.046 mg N m−2 h−1 and the C. muliensis stand about 0.017 ± 0.068 mg N m−2 h−1. Within each stand, we also noted significant variations of N2O emission. We also observed the significant seasonal and inter-annual variation of N2O fluxes during the study period. The highest N2O emission rate was all recorded in July or August in each year from 2005 to 2007. Compared with the mean value of 2005, we found the drought of 2006 significantly increased N2O emissions by 104 times in the E. valleculosa stand, 45 times in K. tibetica stand, and 18 times in the C. muliensis stand. Though there was no significant relation between standing water depths and N2O emissions, we still considered it related to the spatiotemporal dynamics of soil water regime under climate changeRead More

The Tibetan Plateau and surroundings contain the largest number of glaciers outside the polar regions1. These glaciers are at the headwaters of many prominent Asian rivers and are largely experiencing shrinkage2, which affects the water discharge of large rivers such as the Indus3, 4. The resulting potential geohazards5, 6 merit a comprehensive study of glacier status in the Tibetan Plateau and surroundings. Here we report on the glacier status over the past 30 years by investigating the glacial retreat of 82 glaciers, area reduction of 7,090 glaciers and mass-balance change of 15 glaciers. Systematic differences in glacier status are apparent from region to region, with the most intensive shrinkage in the Himalayas (excluding the Karakorum) characterized by the greatest reduction in glacial length and area and the most negative mass balance. The shrinkage generally decreases from the Himalayas to the continental interior and is the least in the eastern Pamir, characterized by the least glacial retreat, area reduction and positive mass balance. In addition to rising temperature, decreased precipitation in the Himalayas and increasing precipitation in the eastern Pamir accompanied by different atmospheric circulation patterns is probably driving these systematic differencesRead More